Excitation functions for the population of shape isomers in americium nuclei have been studied by triton and proton bombardment of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}$, ${}_{}{}^{242}{}_{}{}^{}\mathrm{Pu}$, and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}$ with triton energies ranging from 10 to 16 MeV and proton energies from 9 to 16 MeV. The reactions studied are ($t, 2n$), ($t, 3n$), and ($p, 2n$) leading to final nuclei ${}_{}{}^{241,243,245}{}_{}{}^{}\mathrm{Am}$, ${}_{}{}^{240,242,244}{}_{}{}^{}\mathrm{Am}$, and ${}_{}{}^{238,239,241,243}{}_{}{}^{}\mathrm{Am}$, respectively. In two cases half-lives were obtained, namely, ${}_{}{}^{240}{}_{}{}^{}\mathrm{Pu}(p, 2n){}_{}{}^{239m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=163\mathrm{}\pm 12$ nsec and ${}_{}{}^{244}{}_{}{}^{}\mathrm{Pu}(t, 2n){}_{}{}^{245m}{}_{}{}^{}\mathrm{Am}$, $T_{\frac{1}{2}}=390\mathrm{}\pm 70$ nsec.

• Received 5 June 1972

DOI:https://doi.org/10.1103/PhysRevC.6.1090